As well known to those skilled in the art, wind turbines generate electricity using the power of a rotor, which is rotated by wind. In general, a tower is installed at a designated height above the ground. In addition, a rotor rotated by wind, a speed increaser to increase the rotational speed of the rotor and a generator coupled to the speed increaser to generate the power are sequentially coupled to the top end portion of the tower.
However, if the speed increaser has the above configuration, the structure of the wind turbine may become complicated, so that the manufacturing cost and the repair and maintenance cost may be increased. In addition, the weight of the wind turbine may be increased, so the structural strength of the tower must be reinforced.
In order to solve the above problem, applicant of the present invention suggests a structure of a wind turbine without a speed increaser, which has been filed on Mar. 24, 2006 and now registered as Korean Patent Registration No. 695012. As shown in FIG. 5, a tower 100 is installed at a designated height above the ground and a rotor 200 having a plurality of rotor blades 202 fixed about a hub 201 is installed at the upper portion of the tower 100. A rotating shaft 300 rotatably coupled to the tower 100 is supported by a bearing 301 behind the rotor 200, and a generator 400 is coupled to a rear end of the rotating shaft 300.
In addition, the generator 400 includes a cylindrical housing 401, a rotating plate 402 rotatably coupled to the rotating shaft 300 in the housing 401, a rotator 403 coupled to the outer peripheral portion of the rotating plate 402, and a stator 404 coupled to an inner peripheral surface of the housing 401 to generate the electromagnetic induction through the interaction with the rotator 403.
However, since the rotating shaft 300 crosses the upper end of the tower 100, the length of the rotating shaft 300 may exceed the diameter of the tower 100, so that the weight of the wind turbine may be increased. In addition, the rotating shaft 300 may be sagged or twisted.